1. (Field of Utilization of the Invention)
This invention relates to a heat-sensitive recording apparatus provided with thermal heads, and more particularly to a large-sized heat-sensitive recording apparatus having an effective width equal to and larger than the width of A-1 size paper.
2. (Prior Art)
A thermal head of a heat-sensitive recording apparatus is used for a printer and a facsimile, and now widespread among the general public. Since this heat-sensitive recording apparatus uses a small-width thermal head having an effective width equal to the width of A-4 size paper or B-4 size paper, the recording of an original of such a width that is other than the width of A-4 and B-4 size paper cannot be done.
3. (Problems to be Solved by the Invention)
It is desired that a heat-sensitive recording system which has a simple construction, and which enables high-speed printing, be applied to a large-sized recording apparatus, such as a plotter which is used as a terminal output unit for a CAD/CAM. Among the thermal heads used for heat-sensitive recording apparatuses, thermal heads of small effective widths equal to the widths of A-4 and B-4 size paper have already been commercialized but it is technically difficult to manufacture thermal heads of large effective widths equal to the widths of A-1 and A-0 size paper. Therefore, thermal heads of such large effective widths have not yet been manufactured, nor have large-sized heat-sensitive recording apparatuses for A-1 and A-0 size recording paper been commercialized.
4. (Means for Solving the Problems)
In order to solve these problems, the present invention is constructed as follows. The generally-used small-width thermal heads having an effective width equal to the width of A-4 size paper or B-4 size paper are arranged in rows, each of which has a plurality of thermal heads, over two parallel platens extending at right angles to the direction in which the recording paper is moved, in such a manner that the thermal heads in different rows are alternately disposed in the direction of the width of the recording paper, whereby the heating resistors in the thermal heads in different rows overlap one another with respect to the direction in which the recording paper is moved.
5. (Function)
Parts of a one-dot line extending in the direction of the width of the recording paper are printed by the thermal heads provided on the upstream side of the moving recording paper. When the printed parts of the one-dot line have reached the positions of the heating resistors in the thermal heads on the downstream side of this recording paper, the remaining parts of the one-dot line are printed by the downstream thermal heads. Thus, the parts of the one dot line which have been printed by the upstream thermal heads and the parts thereof which have been printed by the downstream thermal heads are joined to one another. Consequently, one dot line the length of which is larger than that of a thermal head disposed so as to extend in the direction of the width of the recording paper is obtained.
Accordingly, if the number of the thermal heads provided in a thermal recording apparatus is suitably set, the printing of letters of a width equal to or larger than that of A-1 size paper or A-0 size paper can be easily realized.